Toggle linkage valve actuator

ABSTRACT

A toggle linkage valve actuator actuates a valve so as to obtain from the valve identical responses to above-maximum and belowminimum conditions as sensed by the actuator. The sensed condition is translated into mechanical movement of a piston and yoke assembly to which is pivotally attached a toggle bar biased away from the yoke but limited in its separation therefrom by a first adjustment means. Movement of the assembly away from the valve elicits the desired response as the toggle bar is mechanically connected to the valve. Movement of the assembly towards the valve brings the toggle bar into contact with a second adjustment means which reverses the direction of the toggle bar movement, thereby eliciting the same desired response from the valve.

United States Patent [191 Ellett [5 TOGGLE LINKAGE vALvE ACTUATOR [76]Inventor: James R. Ellett, 921 1-75th St.,

Edmonton, Alberta, Canada [22] Filed: Oct. 3, 1972 [2]] Appl. N0.:294,749

[52] US. Cl. .Q. 251/58, 74/110 [51] Int, CL, F161: 31/165 [58] Field ofSearch 74/99, 110; 251/58, 62

[56] References Cited UNITED STATES PATENTS 2,435,143 1/1948 Knauth251/58 X 3,486,731 12/1969 Magnaniet a1. 251/58 Primary ExaminerI-ienryT. Klinksiek 2 I O v w v 7.. a 90 [451 Feb, 5, 1974' 571 ABSTRACT Atoggle linkage valve actuator actuates a valve so as to obtain from thevalve identical responses to abovemaximum and below-minimum conditionsas sensed by the actuator. The sensed condition is translated intomechanical movement of a piston and yoke assembly to which is pivotallyattached a toggle bar biased away from the yoke but limited in itsseparation therefrom by a first adjustment means. Movement of theassembly away from the valve elicits the desired response as the togglebar is mechanically connected to the valve. Movement of the assemblytowards the valve brings the toggle bar into contact with a secondadjustment means which reverses the direction of the toggle barmovement, thereby eliciting the same desired response from the valve.

8 Claims, 1 Drawing Figure I 1 TOGGLE LINKAGE VALVE ACTUATOR Thisinvention relates to valve actuators and more particularly to a valveactuator responsive to both maximum and minimum conditions. 1

It is normally the function ofvalve actuators to actuate a valve inresponse to either an increase above a predetermined maximum pressure orto a decrease below a predetermined minimum pressure. 'In fact, mostsituations demand such a valve actuator. Situations do exist howeverwhereby the same response in a valve is required when the measuredquantity is either greater or less than the predetermined maximum orminimum respectively. The valves opposite response is occasioned by ameasured quantity between the minimum and maximum.

' There have been attempts in the past to produce a valve actuationsystem operating as suggested but they have been complex and unwieldy.One such system involves a pressure operated bellows, a beam pivotallyattached thereto, a pair of fulcrums associated with the beam, acounterweight and a mechanism'for opening and closing a valve. Thatsystem is not adjustable as to setting the'minimum and maximum pressuresat which the valve will open and it requires multiple fulcrums.

- The present invention overcomes those problems by providing a valveactuator which is readily adjustable and has but one pivot point. Itprovides an accurate and reliable method of actuating a valve. 7

The valve actuator of the present invention comprises sensing means forresponding to a measurable quantity, a transfer means connected to thesensing means, an actuating means connected to the transfer means andresiliently biased away therefrom and means for adjusting the actuatingmeans with respect to the transfer means.

The invention will now be more fully described with reference to theattached drawing showing a section through the actuator in use.

Valve actuator 10 is shown as being operatively connected to a three-wayvalve 12, which valve is merely illustrative of the valve mechanismswith which the' valve actuator of the present invention mightbe'associated.

Structurally, valve actuator 10 includes a base housing 14 which may beexternally threaded for reception in a pressure conduit or in anyhousing containing an appropriate measurable quantity. While notessential to the invention, housing 14 may be generally cylindrical inshape. Internal threads 16 coact with external threads 18 on projection22 to connect the linkage housing to base housing 20. The connectiontherebetween is sealed by O-ring 24 and locked by set screw 26.Projection 22 is provided with a central longitudi nal bore-28 in whichpiston 30 is slidably received.

At the lower end of piston 30 is an extension 32 of a diameter slightlygreater than that of the piston itself, so as to form a shoulder or step34. An annular spring base plate 36 has its inner diameter such that itwill sit on step 34 and thus retain spring 38 between itself and theunderside of projection 22. In this manner the piston 30 is biased awayfrom housing 20. Extension 32 is slidable within piston guide 40 whichis held within base housing 14. O-rings 44 and 42 seal extension 32 toguide 40 and guide 40 to housing 14 respectively. Piston guide sleeve 46is threaded into housing 14 so that its lower portion 48 locks guide40between itself end of yoke 54 toggle bar 58 is pivotably attached asby pivot pin 60. Toggle bar 58 reverses the direction of yoke 54 and isprovided with a recess 62 in its lower surface substantially above bore68 in piston 30. Extending between the bottom end of bore 68 and the topend of recess 62 is transfer compression spring 64 guided by transferspring guide 66. Spring 64 tends to .bias movable toggle bar 58 awayfrom yoke 54.

The amount that toggle bar 58 may be biased from yoke 54 is determinedand set by low pressure adjusting screw 72. Screw 72 is so positionedthat the free end of toggle bar 58 abuts against the underside of screwhead 76. The height of screw head 76 above yoke 54 and hence thedisplacement of bar 58 away from yoke 54 is adjustable merely by turningscrew 72 in or out with respect to yoke 54. Screw 72 may be locked inposition with lock nut 74.

High pressure adjusting screw 80 is assembled into the top surface ofhousing 20 in a manner to be now described. Retainer 86 is received in ahole in housing 20 and affixed thereto by means of retainer lock nut 84.Retainer 86 has an axial threaded bore'therein (not shown) into whichadjusting screw 80 is threaded. Screw 80 may be locked in position withlock nut 82.

The valve actuator of the present invention will now be described withreference to valve assembly 12 and its own actuator 88. It must beremembered that valve assembly 12 gives two responses and it is desiredthat one of those responses is to be utilized for two separate positionsof actuator 10.

Considering first actuation in response to a belowminimum condition,assume housing 14 is connected to a pressure system whereby the systempressure can act on diaphragm 50. Thus, in a low pressure situation,spring 38 will force piston 30 downwards against diaphragm 50 therebyalso lowering transfer yoke 54, along with low pressure adjusting screw72. The free end of toggle bar 58 is biased against the underside ofscrew head 76 and thus it is also lowered with piston 30. Valveactuating stem 88 is biased towards toggle bar 58 and it too will belowered thereby providing one response in valve 12. As mentionedpreviously, the height of screw head 76 relative to toggle bar 58determines the pressure at which valve 12 responds as desired.

I Consider now actuation in response to an overmaximum condition.Diaphragm 50 will be forced upwardly against extension 32 of piston 30,overcoming the compression forces in spring 38 and raising piston 30along with transfer yoke 54. Continued upward movement will bring theupper surface of toggle bar 58 into contact with the rounded head 78 ofhigh pressure adjusting screw 80, at which point upward movement oftoggle bar 58 ceases. Further upward movement of transfer yoke 54 andthe consequent upward movement of pivot pin 60 causes the toggle bar 58to rock on rounded head 78, thereby lowering the free end of toggle bar58 whereby valve actuating stem 88 is lowered providing a response invalve assembly 12 identical to that provided in the below-minimumcondition.

There is a dimensional consideration related to the length of toggle bar58 and the position of the point of contact of adjusting screw 80 withrespect to pivot pin 60 and valve actuating stem 88. Screw head 78 isdesir ably half way between pivot pin 60 and stem 88 so that motionupwards of pin 60 relative to screw head 78 results in an equal downwardmotion of stem 88. Thus the adjustment of the screw 80 can be readilydetermined and applied thereto to set the maximum pressure point.

In addition to .the main features of the valve actuator hereindescribed, ancillary features now described aid in providing smoothoperation of the actuator Roll pins 90 are mounted in housing to preventrotation of transfer yoke 54 around the axis of piston 30. They permittransfer yoke 54 to move 'easily up or down due to clearance providedtherein for the pins. Within housing 20 is bevelled boss 92 surroundingpiston which connects to a surrounding and ever-deepening groove orditch 94. Ditch 94 connects 'to drain hole 96 located at the lowestpoint thereof. Thus condensation which could seize the piston to thehousing is prevented from entering the clearance fit around the piston.

Housing 20 is also provided with a removable cover, not shown, whichpermits access thereto so that adjustments may be made to the high andlow pressure adjusting screws.

Operation of the valve actuator has been described particularly withreference to above-maximum and below-minimum conditions. Between the twoextremes, valve actuating stem 88 is raised sufficiently to give aresponse in valve assembly 12 different to the response alreadydescribed.

The valve actuator of the present invention has been described primarilyin association with a pressure system which provides the appropriateforces against diaphragm 50. It is contemplated that the valve actuatorcould be used in any system where a mechanical movement proportional toa measurable quantity can be effectively transmitted to piston 30.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

l. A valve actuator for actuating a valve in response to a conditionwhich may be above a maximum allowable condition, below a minimumallowable condition or therebetween, comprising:

a means for sensing said condition;

b transfer means operatively connected to said sensing means;

c actuating means operatively connected to said transfer means;

d first adjustment means for positively setting said minimum allowablecondition with respect to said actuating means; and

e second adjustment means for positively setting said maximum allowablecondition with respect to said actuating means and independently of saidfirst adjustment means;-whereby said actuating means will operate onsaid valve such that said valve will respond identically to saidbelow-minimum and above-maximum conditions.

2. A valve actuator according to claim 1 wherein said first adjustmentmeans includes a first adjusting screw attached to said actuating meansto effect operation of said valve at said minimum condition and whereinsaid second adjustment means includes a second adjusting screw attachedto a housing enclosing said actuating means and engageable with saidactuating means to effect operation of said valve at said maximumcondition.

3. A valve actuator for actuating a valve in response to a conditionwhich may be above a maximum allowable condition, below a minimumallowable condition or therebetween, comprising:

a an elongate housing:

b condition sensing means supported in one end of said housing;

c a transfer piston longitudinally supported in said housing and biasedtowards said sensing means;

d transfer yoke means attached to said piston at an end remote from saidsensing means; e toggle bar means pivotally connectedto said supportmeans and resiliently biased away therefrom;

f first adjustment means for positively setting said minimum allowablecondition with respect to said bar means; and

g second adjustment means for positively setting said maximum allowablecondition with respect to said bar means; whereby said toggle bar meanswill operate on said valve such that said valve will respond identicallyto said above-maximum and belowminimum conditions.

4. A valve actuator according to claim 3 wherein said first adjustmentmeans includes a first adjusting screw attached to said transfer yokemeans and engageable with a free end of said bar means to adjustablylimit the distance said bar means is biased away from said transfer yokemeans and wherein said second adjustment means includes a secondadjusting screw attached to said housing and engageable with said barmeans to limit travel of its free end away from said one end of saidhousing.

5. A valve actuator according to claim 4 wherein said transfer yokemeans includes a first portion extending generally perpendicular fromsaid piston and a second portion generally parallel thereto and locatedlaterally therefrom at a free end of said first portion, said bar meansbeing pivotally attached to a free end of said second portion andextending therefrom towards said piston, said first adjusting screwbeing attached to a third portion of said transfer support meansdiametrically opposed to said first portion.

6. A valve actuator according to claim 5 wherein said bar means isbiased from said transfer yoke means by a transfer spring having one endlocated in a bore in said remote end of said piston, its other endlocated in a recess in said bar positioned substantially concurrent withsaid bore and transfer spring guide within said spring and located insaid bore to maintain said spring in position.

7. A valve actuator according to claim 6 wherein said second adjustingscrew is located between said second portion of said yoke means and saidrecess and acts as a fulcrum to reverse the direction of travel of thefree end of said bar means as said piston and yoke means travel awayfrom said one end of said housing.

8'. A valve actuator according to claim 7 wherein said one end of saidhousing is adapted for operative connection to a condition containingmeans and wherein the other end of said housing is adapted to receive anactuation element engageable with said bar means and connecting saidvalve actuator to said valve.

1. A valve actuator for actuating a valve in response to a conditionwhich may be above a maximum allowable condition, below a minimumallowable condition or therebetween, comprising: a means for sensingsaid condition; b transfer means operatively connected to said sensingmeans; c actuating means operatively connected to said transfer means; dfirst adjustment means for positively setting said minimum allowablecondition with respect to said actuating means; and e second adjustmentmeans for positively setting said maximum allowable condition withrespect to said actuating means and independently of said firstadjustment means; whereby said actuating means will operate on saidvalve such that said valve will respond identically to saidbelow-minimum and abovemaximum conditions.
 2. A valve actuator accordingto claim 1 wherein said first adjustment means includes a firstadjusting screw attached to said actuating means to effect operation ofsaid valve at said minimum condition and wherein said second adjustmentmeans includes a second adjusting screw attached to a housing enclosingsaid actuating means and engageable with said actuating means to effectoperation of said valve at said maximum condition.
 3. A valve actuatorfor actuating a valve in response to a condition which may be above amaximum allowable condition, below a minimum allowable condition ortherebetween, comprising: a an elongate housing: b condition sensingmeans supported in one end of said housing; c a transfer pistonlongitudinally supported in said housing and biased towards said sensingmeans; d transfer yoke means attached to said piston at an end remotefrom said sensing means; e toggle bar means pivotally connected to saidsupport means and resiliently biased away therefrom; f first adjustmentmEans for positively setting said minimum allowable condition withrespect to said bar means; and g second adjustment means for positivelysetting said maximum allowable condition with respect to said bar means;whereby said toggle bar means will operate on said valve such that saidvalve will respond identically to said above-maximum and below-minimumconditions.
 4. A valve actuator according to claim 3 wherein said firstadjustment means includes a first adjusting screw attached to saidtransfer yoke means and engageable with a free end of said bar means toadjustably limit the distance said bar means is biased away from saidtransfer yoke means and wherein said second adjustment means includes asecond adjusting screw attached to said housing and engageable with saidbar means to limit travel of its free end away from said one end of saidhousing.
 5. A valve actuator according to claim 4 wherein said transferyoke means includes a first portion extending generally perpendicularfrom said piston and a second portion generally parallel thereto andlocated laterally therefrom at a free end of said first portion, saidbar means being pivotally attached to a free end of said second portionand extending therefrom towards said piston, said first adjusting screwbeing attached to a third portion of said transfer support meansdiametrically opposed to said first portion.
 6. A valve actuatoraccording to claim 5 wherein said bar means is biased from said transferyoke means by a transfer spring having one end located in a bore in saidremote end of said piston, its other end located in a recess in said barpositioned substantially concurrent with said bore and transfer springguide within said spring and located in said bore to maintain saidspring in position.
 7. A valve actuator according to claim 6 whereinsaid second adjusting screw is located between said second portion ofsaid yoke means and said recess and acts as a fulcrum to reverse thedirection of travel of the free end of said bar means as said piston andyoke means travel away from said one end of said housing.
 8. A valveactuator according to claim 7 wherein said one end of said housing isadapted for operative connection to a condition containing means andwherein the other end of said housing is adapted to receive an actuationelement engageable with said bar means and connecting said valveactuator to said valve.